IBM Support

IT39306: THE OPTIMIZER MIGHT FAVOUR A NON-OPTIMAL PLAN WITH REGISTRY VARIABLE DB2_EXTENDED_OPTIMIZATION=NLJN_OFLOW

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APAR status

  • Closed as program error.

Error description

  • When the registry variable DB2_EXTENDED_OPTIMIZATION=NLJN_OFLOW
    is set, the optimizer might favour a sub-optimal NLJOIN when the
    table accessed on the inner has overflow records.
    The inner of the NLJOIN will consist of either an index
    oring(IXOR), index anding(IXAND), or list prefetch (LPREFETCH)
    access plan.
    The NLJOIN choice is more likely to be non-optimal when all, or
    most of the rows in the inner qualify the join.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * all                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to 11.1.4.7                                          *
    ****************************************************************
    

Problem conclusion

  • Upgrade to 11.1.4.7
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT39306

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2021-12-03

  • Closed date

    2022-04-17

  • Last modified date

    2022-04-17

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

    IT39586

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • RB10 PSN

       UP

[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSEPGG","label":"DB2 for Linux- UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

Document Information

Modified date:
04 May 2022